Bend Allowance and Developed Length Calculation for Pressbrake Bending

1997 ◽  
Vol 119 (2) ◽  
pp. 227-237 ◽  
Author(s):  
F. Pourboghrat ◽  
K. A. Stelson
Keyword(s):  
Strain Hardening ◽  
Sheet Metal ◽  
Material Properties ◽  
Empirical Equation ◽  
Measured Data ◽  
Neutral Axis ◽  
Physically Based

Developed length refers to the length of the unstretched fiber measured over both bent and straight sections of a bent sheet. Bend allowance is a term coined by Sachs as a measure of the length of the unstretched fiber in the bent section. Sachs’ empirical equation for calculating bend allowance is not physically based and is independent of material and forming conditions. A physics-based model for calculating bend allowance and developed length for a strain hardening sheet metal formed by pressbrake bending is presented. Effects of material properties and tooling geometry on the calculation of these parameters are considered. It is shown that unlike Sachs’ assumption, it is the deformed shape and not the neutral axis shift or thinning that is important for calculating the developed length in pressbrake bending. It is also shown, by comparing calculated and measured data, that better accuracy can be obtained when the proposed method is used instead of Sachs’ empirical equation.

Acquisition of material properties in production for sheet metal forming processes

2013 ◽  
Author(s):  
Jörg Heingärtner ◽  
Anja Neumann ◽  
Dirk Hortig ◽  
Yasar Rencki ◽  
Pavel Hora
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Material Properties ◽  
Metal Forming

STUDY ON SAFETY OF PULLING DOWN COLUMNS IN BUILDING DEMOLITION

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hiroki Takahashi ◽  
Seiji Takanashi ◽  
Hori Tomohito ◽  
Ohdo Katsutoshi ◽  
Hino Yasumiti
Keyword(s):  
Numerical Analysis ◽  
Material Properties ◽  
Neutral Axis ◽  
Cutting Pattern ◽  
Building Demolition

When walls and columns are demolished during the demolition of buildings in Japan, the lower parts of the walls and columns are cut, after which they are pulled down. This method is called the fall-down method. However, the amount of cutting required is unknown. If a worker cuts the columns too deeply, the walls and columns will collapse and may crush the worker. In this study, the fall-down test of columns was carried out to assess the safety of cutting the lower part of columns. The parameters of the test included the pattern of cutting the lower part of columns and the material properties of the model. In addition, the position of the neutral axis was examined by numerical analysis. The results showed that the cutting pattern involving leaving the main reinforcement at the front of the fall-down and cutting the concrete near the neutral axis is safe at demolition sites. In contrast, the cutting pattern with one row of main reinforcement at the front was unsafe and could potentially lead to premature collapse. Columns at demolition sites should not be cut by this latter cutting pattern. The test and the analysis in this study reproduce the demolition site, and the results of these be widely applied in the actual demolition site.

A Real-Time Haptics-Based Deformable Model for Virtual Prototyping and Simulations

2009 ◽  
Author(s):  
Jinling Wang ◽  
Wen F. Lu
Keyword(s):  
Real Time ◽  
Material Properties ◽  
Computer Animation ◽  
Force Feedback ◽  
Haptic Feedback ◽  
Simulation System ◽  
Deformable Model ◽  
Chain Model ◽  
Physically Based ◽  
Update Rate

Virtual reality technology plays an important role in the fields of product design, computer animation, medical simulation, cloth motion, and many others. Especially with the emergence of haptics technology, virtual simulation system provides an intuitive way of human and computer interaction, which allows user to feel and touch the virtual environment. For a real-time simulation system, a physically based deformable model including complex material properties with a high resolution is required. However, such deformable model hardly satisfies the update rate of interactive haptic rendering that exceeds 1 kHz. To tackle this challenge, a real-time volumetric model with haptic feedback is developed in this paper. This model, named as Adaptive S-chain model, extends the S-chain model and integrates the energy-based wave propagation method by the proposed adaptive re-mesh method to achieve realistic graphic and haptic deformation results. The implemented results show that the nonlinear, heterogeneous, anisotropic, shape retaining material properties and large range deformation are well modeled. An accurate force feedback is generated by the proposed Adaptive S-chain model in case study which is quite close to the experiment data.

Wavelet spectrum estimation

Geophysics ◽  
1999 ◽  
Vol 64 (6) ◽  
pp. 1836-1846 ◽  
Author(s):  
Tik Hing Tan
Keyword(s):  
Material Properties ◽  
Pressure Field ◽  
Wavelet Spectrum ◽  
Measured Data ◽  
Complex Spectrum ◽  
Spectrum Estimation ◽  
Wave Propagation Velocity ◽  
Complex Source ◽  
Individual Source ◽  
Source Array

A method for complex source signature estimation for offshore acquisition is presented. Although the wave‐propagation velocity in the water is assumed to be known, no assumptions about the material properties underwater are made. The inputs to the algorithm are the pressure field measured along an end of spread streamer cable, the coordinates of the sources, and the depth of the cable. The output is the complex spectrum of each individual source in the source array. This article discusses the physical interpretation of the equations. It is shown that the estimated wavelets depend on the direct field only. The sensitivities of the method are also discussed. Application of the algorithm on generated and measured data is presented.

Plastic Collapse of Thin Internally Pressurized Torispherical Shells

1979 ◽  
Vol 101 (4) ◽  
pp. 311-320 ◽  
Author(s):  
S. K. Radhamohan ◽  
G. D. Galletly
Keyword(s):  
Strain Hardening ◽  
Yield Stress ◽  
Material Properties ◽  
Parametric Study ◽  
Companion Paper ◽  
Experimental Results ◽  
Plastic Collapse ◽  
Approximate Design ◽  
Mode Of Failure ◽  
Hardening Coefficient

The plastic collapse pressures of internally pressurized thin torispherical shells are given in the present paper. The influence of both the geometric parameters (i.e., r/D, RS/D and D/t) and the material properties (yield stress σyp and the strain-hardening coefficient) on the plastic collapse pressures were investigated. Both steel and aluminium shells were analyzed and, based on the present parametric study, approximate design equations for calculating the plastic collapse pressures are suggested. The asymmetric buckling pressures, pcr, for torispherical shells (obtained from a companion paper) are also compared with the plastic collapse pressures, pc, to determine which are the lower and, thus, control the mode of failure. In addition, the approximate design equations for pcr and pc are compared with some experimental results on small machined models; the agreement between theory and test was quite good.

A “new” empirical equation to describe the strain hardening behavior of steels and other metallic materials

2021 ◽  
Vol 802 ◽  
pp. 140641
Author(s):  
Avala Lavakumar ◽  
Soumya Sourav Sarangi ◽  
Venkat Chilla ◽  
D. Narsimhachary ◽  
Ranjit Kumar Ray
Keyword(s):  
Strain Hardening ◽  
Empirical Equation ◽  
Metallic Materials ◽  
Hardening Behavior ◽  
Strain Hardening Behavior

Novel Concept of Experimental Setup for Characterisation of Plastic Yielding of Sheet Metal at Elevated Temperatures

2005 ◽  
Vol 6-8 ◽  
pp. 657-664 ◽  
Author(s):  
Manfred Geiger ◽  
G. van der Heyd ◽  
Marion Merklein ◽  
Wolfgang Hussnätter
Keyword(s):  
Sheet Metal ◽  
Material Properties ◽  
Room Temperature ◽  
Stress Condition ◽  
Elevated Temperatures ◽  
Biaxial Stress ◽  
Experimental Setup ◽  
Special Importance ◽  
Plastic Yielding ◽  
Novel Concept

In times of highest significance of process modelling and numerical simulation characterisation of material properties is of special importance for tools’ and components’ dimensioning. But in general material properties depend on many different influencing variables, e.g. temperature, humidity and many others. Especially in fields of sheet metal forming the mechanical behaviour of components highly differs according to real stress condition. In particular yield loci combine the information of beginning of yielding with a biaxial stress condition, but nevertheless for many materials they have not been determined yet. For all others the existing values are available only at room temperature. In this paper a novel concept of the experimental setup is shown, with which plastic yielding of sheet metal can be examined also at elevated temperatures. In usual biaxial tension tests cruciform specimen are drawn in plane. The new machine-concept, which is presented in this paper, is based on a punch-load moving perpendicular to the sheet. By clamping the specimen restoring forces are induced, which cause in dependence of special developed tool and work piece geometries defined stress conditions. Using an optical measurement system for determination of strains with CCDcameras of very high frame rate allows exact identification of starting plastification by offline analysis. Experiments at elevated temperatures are realised by local heating with a diode laser and a special optical system to reach a homogenous distribution of temperatures in the forming zone. On the one hand these investigations are necessary for many materials to achieve further information on characteristic properties in warm forming, because their data are only known at room temperature. On the other hand some materials, e.g. magnesium wrought alloys, are mostly formed at elevated temperatures (here in the range of 200°C to 250°C), because of its significant higher formability. Thus, material behaviour must be characterised at these temperatures.

Determination of Residual Stress and Strain-Hardening Exponent Using Artificial Neural Networks

2012 ◽  
Vol 472-475 ◽  
pp. 332-335
Author(s):  
Chun Ping Guan ◽  
Hong Ping Jin
Keyword(s):  
Residual Stress ◽  
Strain Hardening ◽  
Material Properties ◽  
Plastic Material ◽  
Spherical Indentation ◽  
Strain Hardening Exponent ◽  
Stress And Strain ◽  
Ann Model ◽  
Artificial Neural ◽  
Artificial Neural Network Ann

Through dimensional analysis of indentation parameters in this study, we propose an artificial neural network (ANN) model to extract the residual stress and strain-hardening exponent based on spherical indentation. The relationships between indentation parameters and the residual stress and material properties are numerically calibrated through training and validation of the ANN model. They enable the direct mapping of the characteristics of the indentation parameters to the residual stress and the elastic-plastic material properties. The proposed ANN model can be used to quickly and effectively determine the residual stress and strain-hardening exponent.

Investigating the Effect of Miniaturization on the Microtensile Properties of Brass (CuZn30)

2011 ◽  
Author(s):  
Lauren B. Wuertemberger ◽  
Megan N. Chann ◽  
Richard M. Onyancha
Keyword(s):  
Strain Hardening ◽  
Tensile Properties ◽  
Material Properties ◽  
Tensile Tests ◽  
Strain Hardening Exponent ◽  
Manufacturing Processes ◽  
Strength Coefficient ◽  
Grain Sizes ◽  
Heat Treated ◽  
Average Grain Size

As everyday equipment becomes smaller and smaller, it is of increasing importance that the manufacturing processes used for metals are capable of producing parts of appropriate sizes. Currently, manufacturing processes assume macromaterial properties can be applied for microscale production, but is this a valid assumption? This paper investigates the accuracy of applying macroscale tensile properties in microscale applications. In order to test the soundness of this supposition, tensile tests were performed on both macroscale and microscale brass specimens, and the resulting calculated material properties, strain hardening exponent (n) and strength coefficient (K), were compared. Specimens were heat treated to various temperatures before tensile tests were performed, and the strength coefficient and strain hardening exponents of micro and macro tensile specimens were compared. Additionally, it is investigated whether average grain size correlates to material properties. The results showed that in general it is not accurate to apply macroscale tensile properties to microscale applications. However, at mesocale grain sizes, (12–20 microns), the strain hardening exponent values were similar for both macro and microscale specimens.

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